Fabry-Perot interference filter

ABSTRACT

A Fabry-Perot interference filter includes a substrate that has a first surface, a first laminate that has a first mirror portion disposed on the first surface, a second laminate that has a second mirror portion facing the first mirror portion via a gap on a side opposite to the substrate with respect to the first mirror portion, and an intermediate layer that defines the gap between the first laminate and the second laminate. An outer surface of the intermediate layer is curved such that an edge portion of the intermediate layer on the substrate side is positioned on an outer side of an edge portion of the intermediate layer on the side opposite to the substrate in a direction parallel to the first surface. The second laminate covers the outer surface of the intermediate layer.

TECHNICAL FIELD

An aspect of the present invention relates to a Fabry-Perot interferencefilter.

BACKGROUND ART

Patent Literature 1 discloses a Fabry-Perot interferometer including asubstrate, a first mirror structure that has a lower fixed mirrordisposed on the substrate, a second mirror structure that has an uppermovable mirror facing the lower fixed mirror via a space, and asacrificial layer that defines the space between the first mirrorstructure and the second mirror structure. In this Fabry-Perotinterferometer, an outer surface of the sacrificial layer is exposed. Inaddition, the outer surface of the sacrificial layer exhibits a flatsurface shape, is orthogonal to a surface on a side opposite to thefirst mirror structure in the sacrificial layer, and is flush with anouter surface of the second mirror structure.

CITATION LIST Patent Literature

Patent Literature 1: PCT Japanese Translation Patent Publication No.2012-528345

SUMMARY OF INVENTION Technical Problem

In a Fabry-Perot interferometer as described above, since an outersurface of a sacrificial layer is exposed, light is incident from theouter surface of the sacrificial layer. Even if such light has awavelength different from a wavelength corresponding to a distancebetween a lower fixed mirror and an upper movable mirror, there isconcern that the light may be transmitted through the lower fixed mirrorand may be incorporated into light output from the Fabry-Perotinterferometer. In this case, noise in output light increases, so thatcharacteristics of the Fabry-Perot interferometer deteriorate.

In addition, in a Fabry-Perot interferometer as described above, in astate in which a second mirror structure is supported by the sacrificiallayer, the upper movable mirror moves to the lower fixed mirror side dueto an electrostatic force. Consequently, when the upper movable mirrormoves to the lower fixed mirror side, a force acts toward the uppermovable mirror side with respect to a region of the second mirrorstructure supported by the sacrificial layer. Then, due to reaction ofthe force, stress acts on a region of the sacrificial layer supportingthe upper movable mirror. Particularly, in this Fabry-Perotinterferometer, the outer surface of the sacrificial layer exhibits aflat surface shape, is orthogonal to a surface on a side opposite to afirst mirror structure in the sacrificial layer, and is flush with anouter surface of the second mirror structure. Consequently, stress islikely to be concentrated on the outer surface of the sacrificial layerin a corner portion on the second mirror structure side. As a result,there is concern that damage such as a crack may be caused in the cornerportion.

Accordingly, an object of an aspect of the present invention is toprovide a Fabry-Perot interference filter in which high reliability canbe achieved.

Solution to Problem

According to an aspect of the present invention, there is provided aFabry-Perot interference filter including a substrate that has a firstsurface, a first layer that has a first mirror portion disposed on thefirst surface, a second layer that has a second mirror portion facingthe first mirror portion via a gap on a side opposite to the substratewith respect to the first mirror portion, and an intermediate layer thatdefines the gap between the first layer and the second layer. An outersurface of the intermediate layer is curved such that an edge portion ofthe intermediate layer on the substrate side is positioned on an outerside of an edge portion of the intermediate layer on the side oppositeto the substrate in a direction parallel to the first surface. Thesecond layer covers the outer surface of the intermediate layer.

In this Fabry-Perot interference filter, the second layer covers theouter surface of the intermediate layer. Consequently, noise can beprevented from being increased in light output from the Fabry-Perotinterference filter due to incident light from the outer surface of theintermediate layer. Therefore, characteristics of the Fabry-Perotinterference filter can be prevented from deteriorating. Incidentally,in this Fabry-Perot interference filter, since the second layer coversthe outer surface of the intermediate layer, when the second mirrorportion moves to the first mirror portion side, a force also acts towardthe second mirror portion side with respect to a region of the secondlayer covering the outer surface of the intermediate layer. Therefore,stress is likely to be concentrated in a corner portion on the outersurface of the intermediate layer on the second layer side. Here, inthis Fabry-Perot interference filter, the outer surface of theintermediate layer is curved such that the edge portion of theintermediate layer on the substrate side is positioned on the outer sideof the edge portion of the intermediate layer on the side opposite tothe substrate in the direction parallel to the first surface.Consequently, stress can be dispersed in the corner portion on the outersurface of the intermediate layer on the second layer side. Therefore,damage such as a crack can be prevented from being caused in the cornerportion. As described above, according to this Fabry-Perot interferencefilter, high reliability can be achieved.

In the Fabry-Perot interference filter according to the aspect of thepresent invention, the outer surface of the intermediate layer may becurved in a recessed shape on the gap side such that the edge portion ofthe intermediate layer on the substrate side is positioned on the outerside of the edge portion of the intermediate layer on the side oppositeto the substrate in the direction parallel to the first surface. In thiscase, the angle of the outer surface of the intermediate layer withrespect to the first surface decreases in a part close to the substrateon the outer surface of the intermediate layer while becoming close tothe substrate in the direction perpendicular to the first surface.Accordingly, the second layer can be prevented from peeling from a partclose to the substrate on the outer surface of the intermediate layer.

In the Fabry-Perot interference filter according to the aspect of thepresent invention, the outer surface of the intermediate layer may becurved so as to be away from the gap in the direction parallel to thefirst surface while becoming close to the substrate in a directionperpendicular to the first surface. In this case, the outer surface ofthe intermediate layer in its entirety is separated from the gap in thedirection parallel to the first surface while becoming close to thesubstrate in the direction perpendicular to the first surface.Accordingly, stress can be further dispersed in the corner portion onthe outer surface of the intermediate layer on the second layer side.

In the Fabry-Perot interference filter according to the aspect of thepresent invention, an outer surface of the first layer may be positionedon the outer side of the outer surface of the intermediate layer in thedirection parallel to the first surface. The second layer may cover theouter surface of the first layer. In this case, the second layer coversa range to the outer surface of the first layer beyond the outer surfaceof the intermediate layer and is fixed to the outer surface of the firstlayer. Thus, the second layer can be prevented from peeling from a partclose to the substrate on the outer surface of the intermediate layer.

In the Fabry-Perot interference filter according to the aspect of thepresent invention, the substrate may have an outer edge portionpositioned on the outer side of an outer edge of the first layer in acase of being seen in the direction perpendicular to the first surface.The second layer may cover the outer edge portion. In this case, thesecond layer covers a range to the outer edge portion of the substratebeyond the outer edge of the first layer, so that the first layer isfixed to the substrate side. Thus, the first layer can be prevented frompeeling from the substrate side.

In the Fabry-Perot interference filter according to the aspect of thepresent invention, the outer surface of the first layer may be curved soas to be away from the gap in the direction parallel to the firstsurface while becoming close to the substrate in the directionperpendicular to the first surface. In this case, the second layer ismore firmly fixed to the outer surface of the first layer. Thus, thesecond layer can be more reliably prevented from peeling from a partclose to the substrate on the outer surface of the intermediate layer.

According to the aspect of the present invention, the Fabry-Perotinterference filter may further include a third layer that is disposedon a second surface opposite to the first surface in the substrate. Inthis case, it is possible to reduce stress caused by discordance of alayer configuration between the first surface side and the secondsurface side of the substrate. Therefore, concentration of stress in theintermediate layer can be further prevented.

Advantageous Effects of Invention

According to the aspect of the present invention, it is possible toprovide a Fabry-Perot interference filter in which high reliability canbe achieved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of a Fabry-Perot interference filter according toan embodiment of the present invention.

FIG. 2 is a bottom view of the Fabry-Perot interference filter in FIG.1.

FIG. 3 is a cross-sectional view of the Fabry-Perot interference filtertaken along line III-III in FIG. 1.

FIG. 4 is an enlarged cross-sectional view of a first terminal part ofthe Fabry-Perot interference filter in FIG. 1.

FIG. 5 is an enlarged cross-sectional view of a second terminal part ofthe Fabry-Perot interference filter in FIG. 1.

FIG. 6 is an enlarged cross-sectional view of an outer edge part of theFabry-Perot interference filter in FIG. 1.

FIG. 7 is a view for describing a method of manufacturing theFabry-Perot interference filter in FIG. 1.

FIG. 8 is a view for describing the method of manufacturing theFabry-Perot interference filter in FIG. 1.

FIG. 9 is a view for describing the method of manufacturing theFabry-Perot interference filter in FIG. 1.

FIG. 10 is a view for describing the method of manufacturing theFabry-Perot interference filter in FIG. 1.

FIG. 11 is a view for describing the method of manufacturing theFabry-Perot interference filter in FIG. 1.

FIG. 12 is a view for describing the method of manufacturing theFabry-Perot interference filter in FIG. 1.

FIG. 13 is a view for describing a method of manufacturing a Fabry-Perotinterference filter according to a modification example.

FIG. 14 is a view for describing the method of manufacturing theFabry-Perot interference filter according to the modification example.

FIG. 15 is a view for describing the method of manufacturing theFabry-Perot interference filter according to the modification example.

FIG. 16 is a view for describing the method of manufacturing theFabry-Perot interference filter according to the modification example.

FIG. 17 is a view for describing the method of manufacturing theFabry-Perot interference filter according to the modification example.

FIG. 18 is a view for describing the method of manufacturing theFabry-Perot interference filter according to the modification example.

FIG. 19 is a view for describing the method of manufacturing theFabry-Perot interference filter according to the modification example.

FIG. 20 is a view for describing the method of manufacturing theFabry-Perot interference filter according to the modification example.

FIG. 21 is an enlarged cross-sectional view of the outer edge part ofthe Fabry-Perot interference filter according to the modificationexample.

FIG. 22 is an enlarged cross-sectional view of the outer edge part ofthe Fabry-Perot interference filter according to the modificationexample.

FIG. 23 is an enlarged cross-sectional view of the outer edge part ofthe Fabry-Perot interference filter according to the modificationexample.

FIG. 24 is an enlarged cross-sectional view of the outer edge part ofthe Fabry-Perot interference filter according to the modificationexample.

DESCRIPTION OF EMBODIMENT

Hereinafter, an embodiment of the present invention will be described indetail with reference to the drawings. In the following description, thesame reference signs will be applied to the same or equivalent elements,and duplicated description will be omitted.

As illustrated in FIGS. 1, 2, and 3, a Fabry-Perot interference filter 1includes a substrate 11. The substrate 11 has a first surface 11 a and asecond surface 11 b opposite to the first surface 11 a. On the firstsurface 11 a, a reflection prevention layer 21, a first laminate (firstlayer) 22, an intermediate layer 23, and a second laminate (secondlayer) 24 are laminated in this order. A gap (air gap) S is definedbetween the first laminate 22 and the second laminate 24 by theframe-shaped intermediate layer 23. In addition, first terminals 15 andsecond terminals 16 are provided on the first surface 11 a side of theFabry-Perot interference filter 1. In the following description, adirection toward the gap S side from a side opposite to the gap S withrespect to the frame-shaped intermediate layer 23 will be referred to asan “inner side”. In addition, a direction toward the side opposite tothe gap S from the gap S side with respect to the frame-shapedintermediate layer 23 will be referred to as an “outer side”.

The shape and the positional relationship of each portion in a case ofbeing seen in a direction perpendicular to the first surface 11 a (planview) are as follows. For example, an outer edge of the substrate 11 hasa rectangular shape. The outer edge of the substrate 11 and an outeredge of the second laminate 24 coincide with each other. An outer edgeof the reflection prevention layer 21 and an outer edge of the firstlaminate 22 coincide with each other. The outer edge of the reflectionprevention layer 21 and the outer edge of the first laminate 22 arepositioned on the outer side of an outer edge of the intermediate layer23 with respect to a center portion of the gap S. The substrate 11 hasan outer edge portion 11 c positioned on the outer side of the outeredge of the first laminate 22. For example, the outer edge portion 11 chas a frame shape and surrounds the first laminate 22 in a case of beingseen in the direction perpendicular to the first surface 11 a.

In the Fabry-Perot interference filter 1, light having a predeterminedwavelength is transmitted through a light transmission region 1 adefined in a center portion thereof. For example, the light transmissionregion 1 a is a columnar region. For example, the substrate 11 is madeof silicon, quartz, or glass. When the substrate 11 is made of silicon,the reflection prevention layer 21 and the intermediate layer 23 aremade of silicon oxide, for example. The thickness of the intermediatelayer 23 ranges from several tens of nm to several tens of μm, forexample.

A part corresponding to the light transmission region 1 a in the firstlaminate 22 functions as a first mirror portion 31. The first mirrorportion 31 is disposed on the first surface 11 a with the reflectionprevention layer 21 interposed therebetween. The first laminate 22 isconfigured to have a plurality of polysilicon layers 25 and a pluralityof silicon nitride layers 26 which are alternately laminated one by one.In the present embodiment, a polysilicon layer 25 a, a silicon nitridelayer 26 a, a polysilicon layer 25 b, a silicon nitride layer 26 b, anda polysilicon layer 25 e are laminated on the reflection preventionlayer 21 in this order. The optical thickness of each of the polysiliconlayers 25 and the silicon nitride layers 26 configuring the first mirrorportion 31 is preferably an integer multiple of ¼ of a centertransmission wavelength. The first mirror portion 31 may be directlydisposed on the first surface 11 a without the reflection preventionlayer 21 interposed therebetween.

A part corresponding to the light transmission region 1 a in the secondlaminate 24 functions as a second mirror portion 32. The second mirrorportion 32 faces the first mirror portion 31 via the gap S on a sideopposite to the substrate 11 with respect to the first mirror portion31. The second mirror portion 32 is disposed on the first surface 11 awith the reflection prevention layer 21, the first laminate 22, and theintermediate layer 23 interposed therebetween. The second laminate 24 isconfigured to include a plurality of polysilicon layers 27 and aplurality of silicon nitride layers 28 which are alternately laminatedone by one. In the present embodiment, a polysilicon layer 27 a, asilicon nitride layer 28 a, a polysilicon layer 27 b, a silicon nitridelayer 28 b, and a polysilicon layer 27 c are laminated on theintermediate layer 23 in this order. The optical thickness of each ofthe polysilicon layers 27 and the silicon nitride layers 28 configuringthe second mirror portion 32 is preferably an integer multiple of ¼ ofthe center transmission wavelength.

In the first laminate 22 and the second laminate 24, silicon oxidelayers may be used in place of the silicon nitride layers. In addition,as the material of each layer configuring the first laminate 22 and thesecond laminate 24, titanium oxide, tantalum oxide, zirconium oxide,magnesium fluoride, aluminum oxide, calcium fluoride, silicon,germanium, zinc sulfide, or the like may be used.

In a part corresponding to the gap S in the second laminate 24, aplurality of through-holes 24 b leading from a surface 24 a of thesecond laminate 24 on a side opposite to the intermediate layer 23 tothe gap S are formed. The plurality of through-holes 24 b are formed soas not to substantially affect the function of the second mirror portion32. The plurality of through-holes 24 b are used for forming the gap Sby removing a part of the intermediate layer 23 through etching.

A first electrode 12 is provided in the first laminate 22. Morespecifically, the first electrode 12 is formed in the first mirrorportion 31 such that the light transmission region 1 a is surrounded.The first electrode 12 is formed by doping impurities into thepolysilicon layer 25 c and decreasing resistance. A second electrode 13is formed in the first mirror portion 31 such that the lighttransmission region 1 a is included. The second electrode 13 is formedby doping impurities into the polysilicon layer 25 c and decreasingresistance. The size the second electrode 13 is preferably a size forincluding the entirety of the light transmission region 1 a. However,the size may be approximately the same as the size of the lighttransmission region 1 a.

A third electrode 14 is provided in the second laminate 24. Morespecifically, the third electrode 14 is formed in the second mirrorportion 32. The third electrode 14 faces the first electrode 12 and thesecond electrode 13 via the gap S. The third electrode 14 is formed bydoping impurities into the polysilicon layer 27 a and decreasingresistance.

As illustrated in FIGS. 1 and 4, a pair of first terminals 15 isprovided to face each other while having the light transmission region 1a therebetween. Each of the first terminals 15 is disposed inside athrough-hole leading from the surface 24 a of the second laminate 24 tothe first laminate 22. Each of the first terminals 15 is electricallyconnected to the first electrode 12 through a wiring 12 a. For example,the first terminals 15 are formed from a metal film made of aluminum oran alloy thereof.

As illustrated in FIGS. 1 and 5, a pair of second terminals 16 isprovided to face each other while having the light transmission region 1a therebetween. Each of the second terminals 16 is disposed inside athrough-hole leading from the surface 24 a of the second laminate 24 tothe first laminate 22. Each of the second terminals 16 is electricallyconnected to the second electrode 13 through a wiring 13 a and iselectrically connected to the third electrode 14 through a wiring 14 a.

For example, the second terminals 16 are formed from a metal film madeof aluminum or an alloy thereof. The facing direction of the pair offirst terminals 15 and the facing direction of the pair of secondterminals 16 are orthogonal to each other.

As illustrated in FIGS. 3, 4, and 5, a trench 18 is provided on asurface 22 b of the first laminate 22. The trench 18 annularly extendsalong an inner edge of the first electrode 12. The trench 18electrically insulates the first electrode 12 and a region of the firstelectrode 12 on the inner side (second electrode 13). The region insidethe trench 18 may be an insulating material or a gap.

A trench 19 is provided in the second laminate 24. The trench 19annularly extends to surround the first terminals 15. The trench 19electrically insulates the first terminals 15 and the third electrode14. In the present embodiment, the region inside the trench 19 is a gap.However, the region may be an insulating material.

In addition, a trench 20 is provided on the surface 22 b of the firstlaminate 22. The trench 20 annularly extends to surround the secondterminals 16. The trench 20 electrically insulates the second terminals16 and the first electrode 12. The trench 20 is constituted by causingthe intermediate layer 23 to enter a groove portion 25 d which is formedtoward the substrate 11 side by removing a part of the polysilicon layer25 c configuring the first laminate 22. When the intermediate layer 23enters the groove portion 25 d, a surface 23 a of the intermediate layer23 forms a groove portion 23 c toward the substrate 11 side in a regioncorresponding to the groove portion 25 d. In addition, when the secondlaminate 24 enters the groove portion 23 c, the surface 24 a of thesecond laminate 24 forms a groove portion 24 c toward the substrate 11side in a region corresponding to the groove portion 23 c. When thesecond laminate 24 enters the groove portion 23 c in this way, thesecond laminate 24 is fixed to the surface 23 a of the intermediatelayer 23. Accordingly, the second laminate 24 is prevented from peelingfrom the intermediate layer 23. The trench 20 may be constituted bycausing the intermediate layer 23 to enter a groove portion which isformed toward the substrate 11 side by removing a part of the siliconnitride layer 26 b, in addition to a part of the polysilicon layer 25 cconfiguring the first laminate 22.

As illustrated in FIGS. 4 to 6, the intermediate layer 23 has a firstinner surface 23 d formed to surround the first terminals 15, a secondinner surface 23 e formed to surround the second terminals 16, and anouter surface 23 b configuring the outer edge of the intermediate layer23.

As illustrated in FIG. 4, the first inner surface 23 d is curved suchthat an edge portion 23 g of the intermediate layer 23 on the substrate11 side is positioned on the first terminals 15 side of an edge portion23 f of the intermediate layer 23 on the side opposite to the substrate11 in a direction parallel to the first surface 11 a (that is, acontinuously curved surface is formed). That is, in a case of being seenin the direction perpendicular to the first surface 11 a, the edgeportion 23 f surrounds the edge portion 23 g. More specifically, thefirst inner surface 23 d is curved in a recessed shape on a sideopposite to the first terminals 15 in a cross section perpendicular tothe first surface 11 a. An end portion of the first inner surface 23 don the first laminate 22 side is smoothly connected to the surface 22 bof the first laminate 22. The first inner surface 23 d illustrated inFIG. 4 is curved in a recessed shape on the side opposite to the firstterminals 15 so as to be close to the first terminals 15 in thedirection parallel to the first surface 11 a while becoming close to thesubstrate 11 in the direction perpendicular to the first surface 11 a.In other words, on the first inner surface 23 d illustrated in FIG. 4,the angle of the first inner surface 23 d with respect to the firstsurface 11 a decreases while becoming close to the substrate 11 in thedirection perpendicular to the first surface 11 a.

As illustrated in FIG. 5, the second inner surface 23 e is curved suchthat an edge portion 23 i of the intermediate layer 23 on the substrate11 side is positioned on the second terminals 16 side of an edge portion23 h of the intermediate layer 23 on the side opposite to the substrate11 in the direction parallel to the first surface 11 a (that is, acontinuously curved surface is formed). That is, in a case of being seenin the direction perpendicular to the first surface 11 a, the edgeportion 23 h surrounds the edge portion 23 i. More specifically, thesecond inner surface 23 e is curved in a recessed shape on a sideopposite to the second terminals 16 in a cross section perpendicular tothe first surface 11 a. An end portion of the second inner surface 23 eon the first laminate 22 side is smoothly connected to the surface 22 bof the first laminate 22. The second inner surface 23 e illustrated inFIG. 5 is curved in a recessed shape on the side opposite to the secondterminals 16 so as to be close to the second terminals 16 in thedirection parallel to the first surface 11 a while becoming close to thesubstrate 11 in the direction perpendicular to the first surface 11 a.In other words, in the second inner surface 23 e illustrated in FIG. 5,the angle of the second inner surface 23 e with respect to the firstsurface 11 a decreases while becoming close to the substrate 11 in thedirection perpendicular to the first surface 11 a.

As illustrated in FIG. 6, the outer surface 23 b is curved such that anedge portion 23 k of the intermediate layer 23 on the substrate 11 sideis positioned on the outer side of an edge portion 23 j of theintermediate layer 23 on the side opposite to the substrate 11 in thedirection parallel to the first surface 11 a(that is, a continuouslycurved surface is formed). That is, in a case of being seen in thedirection perpendicular to the first surface 11 a, the edge portion 23 ksurrounds the edge portion 23 j. More specifically, the outer surface 23b is curved in a recessed shape on the gap S side in a cross sectionperpendicular to the first surface 11 a. An end portion of the outersurface 23 b on the first laminate 22 side is smoothly connected to thesurface 22 b or an outer surface 22 a of the first laminate 22. Theouter surface 23 b illustrated in FIG. 6 is curved in a recessed shapeon the gap S side so as to be away from the gap S in the directionparallel to the first surface 11 a while becoming close to the substrate11 in the direction perpendicular to the first surface 11 a. In otherwords, in the outer surface 23 b illustrated in FIG. 6, the angle of theouter surface 23 b with respect to the first surface 11 a decreaseswhile becoming close to the substrate 11 in the direction perpendicularto the first surface 11 a.

The first laminate 22 has the outer surface 22 a configuring the outeredge of the first laminate 22. The outer surface 22 a of the firstlaminate 22 is positioned on the outer side in the direction parallel tothe first surface 11 a of the outer surface 23 b of the intermediatelayer 23 with respect to the center portion of the gap S. The outersurface 22 a of the first laminate 22 is curved so as to be away fromthe gap S in the direction parallel to the first surface 11 a whilebecoming close to the substrate 11 in the direction perpendicular to thefirst surface 11 a (that is, a continuously curved surface is formed).More specifically, the outer surface 22 a of the first laminate 22 iscurved in a projected shape on the side opposite to the gap S in thedirection parallel to the first surface 11 a. In other words, on theouter surface 22 a of the first laminate 22, the angle of the outersurface 22 a of the first laminate 22 with respect to the first surface11 a increases while becoming close to the substrate 11 in the directionperpendicular to the first surface 11 a.

As illustrated in FIG. 4, the second laminate 24 further has a firstcovering portion 33 a and a first inner bottom portion 35 a. The firstcovering portion 33 a and the first inner bottom portion 35 a have thesame laminated structure as the second mirror portion 32 (refer to FIG.3) and are integrally formed to be connected to each other. The firstcovering portion 33 a covers the surface 23 a of the intermediate layer23 on the side opposite to the substrate 11, and the first inner surface23 d and leads to the first laminate 22. The first inner bottom portion35 a is formed on the first laminate 22 in a region surrounded by thefirst inner surface 23 d in a case of being seen in the directionperpendicular to the first surface 11 a.

As illustrated in FIG. 5, the second laminate 24 further has a secondcovering portion 33 b and a second inner bottom portion 35 b. The secondcovering portion 33 b and the second inner bottom portion 35 b have thesame layer structure as a part of the laminated structure of the secondmirror portion 32 (refer to FIG. 3) and are integrally formed to beconnected to each other. The second covering portion 33 b covers thesurface 23 a of the intermediate layer 23 on the side opposite to thesubstrate 11, and the second inner surface 23 e and leads to the firstlaminate 22. The second inner bottom portion 35 b is formed on the firstlaminate 22 in a region surrounded by the second inner surface 23 e in acase of being seen in the direction perpendicular to the first surface11 a.

As illustrated in FIG. 6, the second laminate 24 further has a thirdcovering portion 33 c and a peripheral edge portion 34. The thirdcovering portion 33 c and the peripheral edge portion 34 have the samelaminated structure as each other as the second mirror portion 32 (referto FIG. 3) and are integrally formed to be connected to each other. Thethird covering portion 33 c surrounds the second mirror portion 32 in acase of being seen in the direction perpendicular to the first surface11 a. The third covering portion 33 c covers the surface 23 a of theintermediate layer 23 on the side opposite to the substrate 11, theouter surface 23 b of the intermediate layer 23, the outer surface 22 aof the first laminate 22, and a side surface 21 a of the reflectionprevention layer 21 and leads to the first surface 11 a. That is, thethird covering portion 33 c covers the outer edge of the intermediatelayer 23, the outer edge of the first laminate 22, and the outer edge ofthe reflection prevention layer 21.

The peripheral edge portion 34 surrounds the third covering portion 33 cin a case of being seen in the direction perpendicular to the firstsurface 11 a. The peripheral edge portion 34 is positioned on the firstsurface 11 a in the outer edge portion 11 c. That is, the peripheraledge portion 34 covers the outer edge portion 11 c. An outer edge of theperipheral edge portion 34 coincides with the outer edge of thesubstrate 11 in a case of being seen in the direction perpendicular tothe first surface 11 a.

The peripheral edge portion 34 is thinned along an outer edge of theouter edge portion 11 c. That is, a part along the outer edge of theouter edge portion 11 c in the peripheral edge portion 34 is thinnedcompared to other parts excluding the part along the outer edge in theperipheral edge portion 34. In the present embodiment, the peripheraledge portion 34 is thinned by removing a part of the polysilicon layers27 and the silicon nitride layers 28 configuring the second laminate 24.The peripheral edge portion 34 has a non-thinned portion 34 a connectedto the third covering portion 33 c, and a thinned portion 34 bsurrounding the non-thinned portion 34 a. In the thinned portion 34 b,the polysilicon layers 27 and the silicon nitride layers 28 are removed,excluding the polysilicon layer 27 a directly provided on the firstsurface 11 a.

The height of a surface 34 c of the non-thinned portion 34 a on the sideopposite to the substrate 11 from the first surface 11 a is lower thanthe height of the surface 23 a of the intermediate layer 23 from thefirst surface 11 a. The height of the surface 34 c of the non-thinnedportion 34 a from the first surface 11 a ranges from 100 nm to 5,000 nm,for example. The height of the surface 23 a of the intermediate layer 23from the first surface 11 a ranges from 500 nm to 20,000 nm, forexample, and is greater than the height of the surface 34 c of thenon-thinned portion 34 a from the first surface 11 a. The width of thethinned portion 34 b (distance between an outer edge of the non-thinnedportion 34 a and the outer edge of the outer edge portion 11 c) is equalto or greater than 0.01 times the thickness of the substrate 11. Thewidth of the thinned portion 34 b ranges from 5 μm to 400 μm, forexample. The thickness of the substrate 11 ranges from 500 μm to 800 μm,for example.

A reflection prevention layer 41, a third laminate (third layer) 42, anintermediate layer (third layer) 43, and a fourth laminate (third layer)44 are laminated on the second surface 11 b of the substrate 11 in thisorder. The reflection prevention layer 41 and the intermediate layer 43each have a configuration similar to those of the reflection preventionlayer 21 and the intermediate layer 23. The third laminate 42 and thefourth laminate 44 each have a laminated structure symmetrical to thoseof the first laminate 22 and the second laminate 24 based on thesubstrate 11. The reflection prevention layer 41, the third laminate 42,the intermediate layer 43, and the fourth laminate 44 have a function ofpreventing a warpage of the substrate 11.

The third laminate 42, the intermediate layer 43, and the fourthlaminate 44 are thinned along the outer edge of the outer edge portion11 c. That is, the part along the outer edge of the outer edge portion11 c in the third laminate 42, the intermediate layer 43, and the fourthlaminate 44 is thinned compared to other parts excluding a part along anouter edge in the third laminate 42, the intermediate layer 43, and thefourth laminate 44. In the present embodiment, the third laminate 42,the intermediate layer 43, and the fourth laminate 44 are thinned byremoving the entirety of the third laminate 42, the intermediate layer43, and the fourth laminate 44 in a part overlapping the thinned portion34 b in a case of being seen in the direction perpendicular to the firstsurface 11 a.

An opening 40 a is provided in the third laminate 42, the intermediatelayer 43, and the fourth laminate 44 such that the light transmissionregion 1 a is included. The opening 40 a has a diameter approximatelythe same as the size of the light transmission region 1 a. The opening40 a is open on a light emission side, and a bottom surface of theopening 40 a leads to the reflection prevention layer 41.

A light shielding layer 45 is formed on a surface of the fourth laminate44 on the light emission side. For example, the light shielding layer 45is made of aluminum. A protective layer 46 is formed on a surface of thelight shielding layer 45 and an inner surface of the opening 40 a. Theprotective layer 46 covers the outer edges of the third laminate 42, theintermediate layer 43, the fourth laminate 44, and the light shieldinglayer 45 and covers the reflection prevention layer 41 on the outer edgeportion 11 c. For example, the protective layer 46 is made of aluminumoxide. Optical influence due to the protective layer 46 can bedisregarded by causing the thickness of the protective layer 46 to rangefrom 1 to 100 nm (preferably, approximately 30 nm).

In the Fabry-Perot interference filter 1 configured as described above,if a voltage is applied to a location between the first electrode 12 andthe third electrode 14 through the first terminals 15 and the secondterminals 16, an electrostatic force corresponding to the voltage isgenerated between the first electrode 12 and the third electrode 14. Thesecond mirror portion 32 is attracted to the first mirror portion 31side fixed to the substrate 11 due to the electrostatic force, and thedistance between the first mirror portion 31 and the second mirrorportion 32 is adjusted. In this way, in the Fabry-Perot interferencefilter 1, the distance between the first mirror portion 31 and thesecond mirror portion 32 is changeable.

The wavelength of light transmitted through the Fabry-Perot interferencefilter 1 depends on the distance between the first mirror portion 31 andthe second mirror portion 32 in the light transmission region 1 a.Therefore, the wavelength of transmitting light can be suitably selectedby adjusting the voltage to be applied to a location between the firstelectrode 12 and the third electrode 14. At this time, the secondelectrode 13 has the same potential as that of the third electrode 14.Therefore, the second electrode 13 functions as a compensation electrodeto keep the first mirror portion 31 and the second mirror portion 32flat in the light transmission region 1 a.

In the Fabry-Perot interference filter 1, for example, a spectroscopicspectrum can be obtained by detecting light (output light) transmittedthrough the Fabry-Perot interference filter 1 using a light detectorwhile the voltage to be applied to the Fabry-Perot interference filter 1is changed (that is, while the distance between the first mirror portion31 and the second mirror portion 32 is changed in the Fabry-Perotinterference filter 1).

As described above, in the Fabry-Perot interference filter 1, the thirdcovering portion 33 c of the second laminate 24 covers the outer surface23 b of the intermediate layer 23. Consequently, noise can be preventedfrom being increased in light output from the Fabry-Perot interferencefilter 1 due to incident light from the outer surface 23 b of theintermediate layer 23. Therefore, characteristics of the Fabry-Perotinterference filter 1 can be prevented from deteriorating. Incidentally,in the Fabry-Perot interference filter 1, since the second laminate 24covers the outer surface 23 b of the intermediate layer 23, when thesecond mirror portion 32 moves to the first mirror portion 31 side, aforce also acts toward the second mirror portion 32 side with respect toa region of the second laminate 24 covering the outer surface 23 b ofthe intermediate layer 23. Therefore, stress is likely to beconcentrated in a corner portion on the outer surface 23 b of theintermediate layer 23 on the second laminate 24 side. Here, in theFabry-Perot interference filter 1, the outer surface 23 b of theintermediate layer 23 is curved such that the edge portion 23 k of theintermediate layer 23 on the substrate 11 side is positioned on theouter side in the direction parallel to the first surface 11 a of theedge portion 23 j of the intermediate layer 23 on the side opposite tothe substrate 11. Consequently, stress can be dispersed in the cornerportion on the outer surface 23 b of the intermediate layer 23 on thesecond laminate 24 side. Therefore, damage such as a crack can beprevented from being caused in the corner portion. As described above,according to the Fabry-Perot interference filter 1, high reliability canbe achieved.

In addition, in the Fabry-Perot interference filter 1, compared to acase in which the outer surface 23 b of the intermediate layer 23 is notcurved, a contact area between the outer surface 23 b of theintermediate layer 23 and the second laminate 24 is widened.Consequently, the second laminate 24 can be firmly fixed to the outersurface 23 b of the intermediate layer 23. In addition, the outersurface 23 b of the intermediate layer 23 is curved so as to be awayfrom the gap S in the direction parallel to the first surface 11 a whilebecoming close to the substrate 11 in the direction perpendicular to thefirst surface 11 a. Consequently, in a manufacturing step, the thickness(coverage) of the third covering portion 33 c of the second laminate 24covering the outer surface 23 b of the intermediate layer 23 can befavorably maintained.

In addition, in the Fabry-Perot interference filter 1, the outer surface23 b of the intermediate layer 23 is curved in a recessed shape on thegap S side such that the edge portion 23 k of the intermediate layer 23on the substrate 11 side is positioned on the outer side in thedirection parallel to the first surface 11 a of the edge portion 23 j ofthe intermediate layer 23 on the side opposite to the substrate 11.

Consequently, the angle of the outer surface 23 b of the intermediatelayer 23 with respect to the first surface 11 a decreases in a partclose to the substrate 11 on the outer surface 23 b of the intermediatelayer 23 while becoming close to the substrate 11 in the directionperpendicular to the first surface 11 a. Accordingly, the secondlaminate 24 can be prevented from peeling from a part close to thesubstrate 11 on the outer surface 23 b of the intermediate layer 23.

In addition, in the Fabry-Perot interference filter 1, the outer surface23 b of the intermediate layer 23 is curved so as to be away from thegap S in the direction parallel to the first surface 11 a while becomingclose to the substrate 11 in the direction perpendicular to the firstsurface 11 a. Consequently, the outer surface 23 b of the intermediatelayer 23 in its entirety is separated from the gap S in the directionparallel to the first surface 11 a while becoming close to the substrate11 in the direction perpendicular to the first surface 11 a.Accordingly, stress can be further dispersed in the corner portion onthe outer surface 23 b of the intermediate layer 23 on the secondlaminate 24 side.

In addition, in the Fabry-Perot interference filter 1, the outer surface22 a of the first laminate 22 is positioned on the outer side in thedirection parallel to the first surface 11 a of the outer surface 23 bof the intermediate layer 23 with respect to the center portion of thegap 5, and the third covering portion 33 c of the second laminate 24covers the outer surface 22 a of the first laminate 22. Consequently,the third covering portion 33 c of the second laminate 24 covers a rangeto the outer surface 22 a of the first laminate 22 beyond the outersurface 23 b of the intermediate layer 23 and is fixed to the outersurface 22 a of the first laminate 22. Thus, the second laminate 24 canbe prevented from peeling from a part close to the substrate 11 on theouter surface 23 b of the intermediate layer 23.

In addition, in the Fabry-Perot interference filter 1, in a case ofbeing seen in the direction perpendicular to the first surface 11 a, thesubstrate 11 has the outer edge portion 11 c positioned on the outerside of the outer edge of the first laminate 22, and the second laminate24 covers the outer edge portion 11 c. Consequently, the second laminate24 covers a range to the outer edge portion 11 c of the substrate 11beyond the outer edge of the first laminate 22, so that the firstlaminate 22 is fixed to the substrate 11 side. Thus, the first laminate22 can be prevented from peeling from the substrate 11 side.

In addition, in the Fabry-Perot interference filter 1, the outer surface22 a of the first laminate 22 is curved so as to be away from the gap Sin the direction parallel to the first surface 11 a while becoming closeto the substrate 11 in the direction perpendicular to the first surface11 a. Consequently, the third covering portion 33 c of the secondlaminate 24 is more firmly fixed to the outer surface 22 a of the firstlaminate 22. Thus, the second laminate 24 can be prevented from peelingfrom a part close to the substrate 11 on the outer surface 23 b of theintermediate layer 23.

In addition, the Fabry-Perot interference filter 1 further includes thethird laminate 42 that is disposed on the second surface 11 b oppositeto the first surface 11 a in the substrate 11. Consequently, it ispossible to reduce stress caused by discordance of the layerconfiguration between the first surface 11 a side and the second surface11 b side of the substrate 11. Therefore, concentration of stress in theintermediate layer 23 can be further prevented.

Next, with reference to FIGS. 7 to 12, an example of a method ofmanufacturing the Fabry-Perot interference filter 1 will be described.However, in FIGS. 7 and 10 to 12, the outer surface 22 a of the firstlaminate 22, the outer surface 23 b of the intermediate layer 23, andthe third covering portion 33 c of the second laminate 24 are simplyillustrated. First, as illustrated in FIG. 7(a), a wafer 10 including aplurality of parts R corresponding to the substrate 11 is prepared, andthe first laminate 22 having the first mirror portion 31 is formed foreach of the parts R corresponding to the substrate 11 in the wafer 10(first step). For example, the wafer 10 is a silicon wafer. In the wafer10, for example, the parts R are disposed to be adjacent to each otherin a lattice state. A dicing line L is set on the border between theparts R.

In the first step, first, the reflection prevention layer 21 is formedon the first surface 11 a of the part R. At the same time, thereflection prevention layer 41 is formed on the second surface 11 b ofthe part R. Subsequently, the polysilicon layer 25 a, the siliconnitride layer 26 a, the polysilicon layer 25 b, the silicon nitridelayer 26 b, and the polysilicon layer 25 c configuring the firstlaminate 22 are laminated on the reflection prevention layer 21 in thisorder. At the same time as the first laminate 22 is laminated, apolysilicon layer and a silicon nitride layer configuring the thirdlaminate 42 are laminated on the reflection prevention layer 41. Whenthe first laminate 22 is laminated, the polysilicon layer 25 and thesilicon nitride layer 26 are laminated over the first surface 11 a.Thereafter, a part of the polysilicon layer 25 and the silicon nitridelayer 26 positioned on the outer edge portion lie in a case of beingseen in the direction perpendicular to the first surface 11 a is removedthrough etching. In addition, in parallel with laminating of the firstlaminate 22, the polysilicon layers 25 b and 25 c are partiallydecreased in resistance by doping impurities, so that the firstelectrode 12 and the second electrode 13 are formed. Subsequently, thetrench 18 is formed through etching.

Subsequently, as illustrated in FIG. 7(b), the intermediate layer 23having a portion 50 expected to be removed corresponding to the gap S isformed for each of the parts R (second step). In the second step, first,the intermediate layer 23 is formed over the first surface 11 a of thepart R such that the first laminate 22 is covered with the intermediatelayer 23. At the same time as the intermediate layer 23 is formed, theintermediate layer 43 is formed on the third laminate 42. Subsequently,a part of the intermediate layer 23 positioned on the outer edge portion11 c in a case of being seen in the direction perpendicular to the firstsurface 11 a is removed through etching. During this etching, a part ofthe reflection prevention layer 21 positioned on the outer edge portion11 c in a case of being seen in the direction perpendicular to the firstsurface 11 a is removed. In addition, during this etching, gaps areformed in parts corresponding to the first terminals 15, the firstcovering portion 33 a, and the first inner bottom portion 35 a in FIG.4; and the second terminals 16, the second covering portion 33 b, andthe second inner bottom portion 35 b in FIG. 5.

Moreover, during this etching, the first inner surface 23 d, the secondinner surface 23 e, and the outer surface 23 b are formed to have acurved shape. More specifically, the first inner surface 23 d is formedto be curved in a recessed shape on the side opposite to the firstterminals 15 so as to be close to the first terminals 15 in thedirection parallel to the first surface 11 a while becoming close to thesubstrate 11 in the direction perpendicular to the first surface 11 a.In addition, the second inner surface 23 e is formed to be curved in arecessed shape on the side opposite to the second terminals 16 so as tobe close to the second terminals 16 in the direction parallel to thefirst surface 11 a while becoming close to the substrate 11 in thedirection perpendicular to the first surface 11 a. In addition, theouter surface 23 b is formed to be curved in a recessed shape on the gapS side so as to be away from the gap S in the direction parallel to thefirst surface 11 a while becoming close to the substrate 11 in thedirection perpendicular to the first surface 11 a.

An example of a manufacturing method, in which the first inner surface23 d, the second inner surface 23 e, and the outer surface 23 b areformed to be curved in a recessed shape as described above, will bedescribed. First, as illustrated in FIG. 8(a), a resist M is appliedover the intermediate layer 23. Next, as illustrated in FIG. 8(b),through resist patterning, the resist M is removed from a regioncorresponding to a region of the intermediate layer 23 to be removed.Next, as illustrated in FIG. 9(a), the intermediate layer 23 is removedthrough etching (wet etching). At this time, a range to a part of theintermediate layer 23 covered with the resist M is removed, so that theintermediate layer 23 is formed to be curved in a recessed shape. Thereflection prevention layer 21 and the first laminate 22 are formed instages while repeating film-forming and etching, and etching of theintermediate layer 23 is carried out such that the outer surface 23 b ofthe intermediate layer 23 is continuously (smoothly) connected to theouter surface 22 a of the first laminate 22. Accordingly, as illustratedin FIG. 6, the outer surface 23 b of the intermediate layer 23, theouter surface 22 a of the first laminate 22, and the side surface 21 aof the reflection prevention layer 21 have a continuously curved shape.Next, as illustrated in FIG. 9(b), the resist M remaining on theintermediate layer 23 is stripped off, so that the first inner surface23 d, the second inner surface 23 e, and the outer surface 23 b havingthe shape described above can be obtained.

Subsequently, as illustrated in FIGS. 10(a), 10(b), and 11(a), thesecond laminate 24 having the second mirror portion 32 in which theplurality of through-holes 24 b are formed, the first covering portion33 a which covers the intermediate layer 23, the second covering portion33 b, the third covering portion 33 c, the peripheral edge portion 34thinned along the outer edge of the outer edge portion 11 c, the firstinner bottom portion 35 a, and the second inner bottom portion 35 b areformed for each of the parts R (third step).

In the third step, first, the polysilicon layer 27 a, the siliconnitride layer 28 a, the polysilicon layer 27 b, the silicon nitridelayer 28 b, and the polysilicon layer 27 c configuring the secondlaminate 24 are laminated on the intermediate layer 23 in this order.More specifically, as illustrated in FIG. 10(a), the second laminate 24is laminated over the first surface 11 a of the part R such that thesecond laminate 24 covers the surface 23 a, the outer surface 23 b, thefirst inner surface 23 d, and the second inner surface 23 e of theintermediate layer 23; the outer surface 22 a of the first laminate 22;and the side surface 21 a of the reflection prevention layer 21. On theother hand, at the same time as the second laminate 24 is laminated, thepolysilicon layer and the silicon nitride layer configuring the fourthlaminate 44 are laminated on the intermediate layer 43. Subsequently, asillustrated in FIG. 10(b), a part of the polysilicon layers 27 and thesilicon nitride layers 28 corresponding to the thinned portion 34 b isremoved through etching, excluding the polysilicon layer 27 a, so thatthe peripheral edge portion 34 thinned along the outer edge of the outeredge portion 11 c is formed. In addition, in parallel with laminating ofthe second laminate 24, the polysilicon layer 27 a is partiallydecreased in resistance by doping impurities, and the third electrode 14is formed. Subsequently, the first terminals 15 and the second terminals16 are formed.

Subsequently, as illustrated in FIG. 11(a), the second laminate 24 ispartially etched, so that the through-holes 24 b leading from thesurface 24 a of the second mirror portion 32 to the portion 50 expectedto be removed are formed. Subsequently, the light shielding layer 45 isformed on the fourth laminate 44. Subsequently, a part of the thirdlaminate 42, the intermediate layer 43, the fourth laminate 44, and thelight shielding layer 45 overlapping the thinned portion 34 b in a caseof being seen in a perpendicular direction is removed through etching,so that the third laminate 42, the intermediate layer 43, and the fourthlaminate 44 are thinned along the outer edge of the outer edge portion11 c. In addition, during this etching, the opening 40 a is formed inthe third laminate 42, the intermediate layer 43, the fourth laminate44, and the light shielding layer 45. Subsequently, the protective layer46 is formed on the surface of the light shielding layer 45 and theinner surface of the opening 40 a.

Subsequently, as illustrated in FIG. 11(b), the portion 50 expected tobe removed is removed through etching via the through-holes 24 b, sothat the gap S positioned between the first mirror portion 31 and thesecond mirror portion 32 is formed for each of the parts R (fourthstep). In the fourth step, the portion 50 expected to be removed isremoved through gas phase etching via the through-holes 24 b. In thisgas phase etching, for example, hydrofluoric acid gas is used.

Subsequently, as illustrated in FIG. 12, the wafer 10 is cut along theouter edge of the outer edge portion 11 c in the dicing line L, and thenthe Fabry-Perot interference filter 1 is obtained (fifth step). In thefifth step, for example, the wafer 10 is cut along the outer edge of theouter edge portion 11 c by forming a modified region within the wafer 10along the outer edge of the outer edge portion 11 c through irradiationof laser light from the first surface 11 a side, and extending a crackfrom the modified region in the thickness direction of the wafer 10.

Hereinabove, an embodiment of the present invention has been described.However, the present invention is not limited to the embodimentdescribed above. For example, the material and the shape of each of theconfigurations are not limited to the materials and the shapes describedabove, and various materials and shapes can be employed.

In addition, the reflection prevention layer 21 may be formed in aregion on the outer side of the outer edge of the first laminate 22. Forexample, the reflection prevention layer 21 may also be formed withoutbeing removed in a part of the second laminate 24 corresponding to theperipheral edge portion 34 (that is, a part positioned on the outer edgeportion 11 c). In such a case, the outer edge of the reflectionprevention layer 21 and the outer edge of the substrate 11 may coincidewith each other.

In addition, the substrate 11 does not have to have the outer edgeportion 11 c. For example, in a case of being seen in the directionperpendicular to the first surface 11 a, the outer surface 22 a of thefirst laminate 22 may coincide with the outer edge of the substrate 11.In addition, in a case of being seen in the direction perpendicular tothe first surface 11 a, the side surface 21 a of the reflectionprevention layer 21 may coincide with the outer edge of the substrate11.

In addition, the peripheral edge portion 34 does not have to have thethinned portion 34 b. That is, the peripheral edge portion 34 may beformed to have a uniform thickness throughout the peripheral edgeportion 34 in its entirety.

In addition, the second laminate 24 does not have to have the peripheraledge portion 34. That is, the second laminate 24 does not have to bepositioned on the first surface 11 a.

In addition, the first electrode 12 does not have to be formed as a partof the first mirror portion 31. The first electrode 12 does not have tobe formed by doping impurities into the polysilicon layer 25 c anddecreasing resistance. For example, the first electrode 12 may be formedin a region other than the first mirror portion 31 in the first laminate22. In this case, the first electrode 12 may be formed of metal such asaluminum.

In addition, the second electrode 13 does not have to be formed as apart of the first mirror portion 31. The second electrode 13 does nothave to be formed by doping impurities into the polysilicon layer 25 cand decreasing resistance. For example, the second electrode 13 may beformed in a region other than the first mirror portion 31 in the firstlaminate 22. In this case, the second electrode 13 may be formed ofmetal such as aluminum.

In addition, the third electrode 14 does not have to be formed as a partof the second mirror portion 32. The third electrode 14 does not have tobe formed by doping impurities into the polysilicon layer 27 a anddecreasing resistance. For example, the third electrode 14 may be formedin a region other than the second mirror portion 32 in the secondlaminate 24. In this case, the third electrode 14 may be formed of metalsuch as aluminum.

In addition, the second inner surface 23 e does not have to be curvedsuch that the edge portion 23 i of the intermediate layer 23 on thesubstrate 11 side is positioned on the second terminals 16 side in thedirection parallel to the first surface 11 a of the edge portion 23 h ofthe intermediate layer 23 on the side opposite to the substrate 11.

In addition, the first inner surface 23 d, the second inner surface 23e, or the outer surface 23 b does not have to curved in a recessedshape. In addition, the second laminate 24 does not have to have thefirst inner bottom portion 35 a or the second inner bottom portion 35 band does not have to cover the first inner surface 23 d or the secondinner surface 23 e.

In addition, the manufacturing method, in which the first inner surface23 d, the second inner surface 23 e, and the outer surface 23 b areformed to be curved in a recessed shape in the second step, is notlimited to that described above, and the following manufacturing methodmay be employed. First, as illustrated in FIG. 13(a), the resist M isapplied over the intermediate layer 23. Next, as illustrated in FIG.13(b), the resist M is subjected to exposure and development by using a3D mask. Accordingly, the resist M is removed from a regioncorresponding to a region of the intermediate layer 23 to be removed,and a side surface of the resist M is formed to be curved in a recessedshape. Next, as illustrated in FIG. 14(a), the intermediate layer 23 isremoved though dry etching. Accordingly, the curved recess shape of theside surface of the resist M is copied onto the first inner surface 23d, the second inner surface 23 e, and the outer surface 23 b, which arethereby forming to be curved in a recessed shape. Next, as illustratedin FIG. 14(b), the resist M remaining on the intermediate layer 23 isstripped off, so that the first inner surface 23 d, the second innersurface 23 e, and the outer surface 23 b having the shape describedabove can be obtained.

Alternatively, as a manufacturing method, in which the first innersurface 23 d, the second inner surface 23 e, and the outer surface 23 bare formed to be curved in a recessed shape in the second step, thefollowing manufacturing method may be employed. First, as illustrated inFIG. 15(a), the resist M is applied over the intermediate layer 23.Next, as illustrated in FIG. 15(b), the resist M is subjected tophotolithography to remove the resist M in a region corresponding to aregion of the intermediate layer 23 to be removed, and the side surfaceof the resist M is formed to be curved in a recessed shape. In the stepof performing this photolithography, the side surface of the resist Mcan be formed to be curved in a recessed shape by adjusting conditionsfor the resist M (for example, the material) and conditions forphotolithography (for example, exposure conditions, developmentconditions, and baking conditions). Next, as illustrated in FIG. 16(a),the intermediate layer 23 is removed through dry etching. Accordingly,the curved recess shape of the side surface of the resist M is copiedonto the first inner surface 23 d, the second inner surface 23 e, andthe outer surface 23 b, which are thereby formed to be curved in arecessed shape. Next, as illustrated in FIG. 16(b), the resist Mremaining on the intermediate layer 23 is stripped off, so that thefirst inner surface 23 d, the second inner surface 23 e, and the outersurface 23 b having the shape described above can be obtained.

In addition, the first inner surface 23 d may be curved in a projectedshape on the first terminals 15 side. In other words, on the first innersurface 23 d, the angle of the first inner surface 23 d with respect tothe first surface 11 a may increase while becoming close to thesubstrate 11 in the direction perpendicular to the first surface 11 a.In this case, in a corner portion on the first inner surface 23 d on theside opposite to the first laminate 22, the outer shape of a crosssection thereof has an obtuse angle shape. Thus, stress acting on thecorner portion on the first inner surface 23 d on the side opposite tothe first laminate 22 is further dispersed, so that damage such as acrack can be further prevented from being caused in the corner portion.

In addition, the second inner surface 23 e may be curved in a projectedshape on the second terminals 16 side. In other words, on the secondinner surface 23 e, the angle of the second inner surface 23 e withrespect to the first surface 11 a may increase while becoming close tothe substrate 11 in the direction perpendicular to the first surface 11a. In this case, in a corner portion on the second inner surface 23 e onthe side opposite to the first laminate 22, the outer shape of a crosssection thereof has an obtuse angle shape. Thus, stress acting on thecorner portion on the second inner surface 23 e on the side opposite tothe first laminate 22 is further dispersed, so that damage such as acrack can be further prevented from being caused in the corner portion.

In addition, the outer surface 23 b may be curved in a projected shapeon the side opposite to the gap S. In other words, on the outer surface23 b, the angle of the outer surface 23 b with respect to the firstsurface 11 a may increase while becoming close to the substrate 11 inthe direction perpendicular to the first surface 11 a. In this case, ina corner portion on the outer surface 23 b on the side opposite to thefirst laminate 22, the outer shape of a cross section thereof has anobtuse angle shape. Thus, stress acting on the corner portion on theouter surface 23 b on the side opposite to the first laminate 22 isfurther dispersed, so that damage such as a crack can be furtherprevented from being caused in the corner portion.

An example of a manufacturing method, in which the first inner surface23 d, the second inner surface 23 e, and the outer surface 23 b areformed to be curved in a projected shape as described above in thesecond step of this case, will be described. First, as illustrated inFIG. 17(a), the resist M is applied over the intermediate layer 23.Next, as illustrated in FIG. 17(b), through resist patterning, theresist M is removed from a region corresponding to a region of theintermediate layer 23 to be removed. Next, as illustrated in FIG. 18(a),the resist M is cured. Accordingly, the side surface of the resist M isformed to be curved in a projected shape. Next, as illustrated in FIG.18(b), the intermediate layer 23 is removed through dry etching.Accordingly, a range to a portion near a part of the intermediate layer23 covered with the resist M is removed, and the curved projected shapeof the side surface of the resist M is copied onto the first innersurface 23 d, the second inner surface 23 e, and the outer surface 23 b,which are thereby formed to be curved in a projected shape. Next, asillustrated in FIG. 18(c), the resist M remaining on the intermediatelayer 23 is stripped off, so that the first inner surface 23 d, thesecond inner surface 23 e, and the outer surface 23 b having the shapedescribed above can be obtained.

Alternatively, as a manufacturing method, in which the first innersurface 23 d, the second inner surface 23 e, and the outer surface 23 bare formed to be curved in a projected shape in the second step, thefollowing manufacturing method may be employed. First, as illustrated inFIG. 19(a), the resist M is applied over the intermediate layer 23.Next, as illustrated in FIG. 19(b), the resist M is subjected toexposure and development by using a 3D mask. Accordingly, the resist Mis removed from a region corresponding to a region of the intermediatelayer 23 to be removed, and a side surface of the resist M is formed tobe curved in a projected shape. Next, as illustrated in FIG. 20(a), theintermediate layer 23 is removed through dry etching. Accordingly, arange to a part of the intermediate layer 23 covered with the resist Mis removed, and the curved projection shape of the side surface of theresist M is copied onto the first inner surface 23 d, the second innersurface 23 e, and the outer surface 23 b, which are thereby formed to becurved in a projected shape. Next, as illustrated in FIG. 20(b), theresist M remaining on the intermediate layer 23 is stripped off, so thatthe first inner surface 23 d, the second inner surface 23 e, and theouter surface 23 b having the shape described above can be obtained.

In addition, as illustrated in FIGS. 21 to 24, the outer edge of thereflection prevention layer 21 and the outer edge of the first laminate22 do not have to coincide with each other. In addition, the outersurface 22 a of the first laminate 22 may be configured to be anintermittent surface, instead of a continuous surface. For example, theside surface 21 a of the reflection prevention layer 21 may bepositioned on the inner side (light transmission region 1 a side) of theouter surface 22 a of the first laminate 22. In this case, a part of thepolysilicon layer 27 a of the second laminate 24 enters the inside of agroove formed by the side surface 21 a of the reflection preventionlayer 21, a surface 22 c of the first laminate 22 on the substrate 11side, and the first surface 11 a of the substrate 11. Accordingly, thesecond laminate 24 can be prevented from peeling.

In addition, as illustrated in FIGS. 21 and 22, an outer edge of thepolysilicon layer 25 c of the first laminate 22 may cover at least apart on an outer surface of a layer other than the polysilicon layer 25c of the layers configuring the first laminate 22.

In addition, as illustrated in FIGS. 21 and 22, an outer edge of a layerother than the polysilicon layer 25 c of the layers configuring thefirst laminate 22 may exhibit an intermittent shape (for example, astepped state). For example, an outer edge of the polysilicon layer 25 band an outer edge of the silicon nitride layer 26 b do not have tocoincide with each other. More specifically, an outer surface of thepolysilicon layer 25 b may be positioned on the outer side (on a sideopposite to the light transmission region 1 a) of an outer surface ofthe silicon nitride layer 26 b. Accordingly, the bonded area between thethird covering portion 33 c of the second laminate 24 and the outersurface 22 a of the first laminate 22 increases, so that the secondlaminate 24 can be prevented from peeling.

As illustrated in FIG. 21, the outer surface of a layer other than thepolysilicon layer 25 c of the layers configuring the first laminate 22,and the side surface 21 a of the reflection prevention layer 21 mayexhibit a flat surface shape and may be inclined so as to be away fromthe light transmission region 1 a in the direction parallel to the firstsurface 11 a while becoming close to the substrate 11 in the directionperpendicular to the first surface 11 a.

Alternatively, as illustrated in FIG. 22, the outer surface of a layerother than the polysilicon layer 25 c of the layers configuring thefirst laminate 22, and the side surface 21 a of the reflectionprevention layer 21 may exhibit a flat surface shape and may beapproximately orthogonal to the first surface 11 a.

In addition, as illustrated in FIGS. 23 and 24, in the first laminate22, the outer edge of the polysilicon layer 25 c may be positioned onthe inner side of the outer edge of the silicon nitride layer 26 b. Inthis case as well, the bonded area between the third covering portion 33c of the second laminate 24 and the outer surface 22 a of the firstlaminate 22 increases, so that the second laminate 24 can be preventedfrom peeling.

In addition, the outer surface 22 a of the first laminate 22 may becurved in a recessed shape on the gap S side. In other words, on theouter surface 22 a, the angle of the outer surface 22 a with respect tothe first surface 11 a may decrease while becoming close to thesubstrate 11 in the direction perpendicular to the first surface 11 a.Alternatively, the outer surface 22 a may exhibit a flat surface shapewithout being curved.

REFERENCE SIGNS LIST

-   -   1 Fabry-Perot interference filter    -   11 Substrate    -   11 a First surface    -   22 First laminate (first layer)    -   22 a Outer surface    -   23 Intermediate layer    -   23 b Outer surface    -   23 j, 23 k Edge portion    -   24 Second laminate (second layer)    -   31 First mirror portion    -   32 Second mirror portion    -   42 Third laminate (third layer)    -   43 Intermediate layer (third layer)    -   44 Fourth laminate (third layer)    -   S Gap

The invention claimed is:
 1. A Fabry-Perot interference filtercomprising: a substrate that has a first surface; a first layer that hasa first mirror portion disposed on the first surface; a second layerthat has a second mirror portion facing the first mirror portion via agap on a side opposite to the substrate with respect to the first mirrorportion; and an intermediate layer that defines the gap between thefirst layer and the second layer, wherein an outer surface of theintermediate layer is curved such that an edge portion of theintermediate layer on the substrate side is positioned on an outer sideof an edge portion of the intermediate layer on the side opposite to thesubstrate in a direction parallel to the first surface, and wherein thesecond layer covers the outer surface of the intermediate layer.
 2. TheFabry-Perot interference filter according to claim 1, wherein the outersurface of the intermediate layer is curved in a recessed shape on thegap side such that the edge portion of the intermediate layer on thesubstrate side is positioned on the outer side of the edge portion ofthe intermediate layer on the side opposite to the substrate in thedirection parallel to the first surface.
 3. The Fabry-Perot interferencefilter according to claim 1, wherein the outer surface of theintermediate layer is curved so as to be away from the gap in thedirection parallel to the first surface while becoming close to thesubstrate in a direction perpendicular to the first surface.
 4. TheFabry-Perot interference filter according to claim 1, wherein an outersurface of the first layer is positioned on the outer side of the outersurface of the intermediate layer in the direction parallel to the firstsurface, and wherein the second layer covers the outer surface of thefirst layer.
 5. The Fabry-Perot interference filter according to claim4, wherein the substrate has an outer edge portion positioned on theouter side of an outer edge of the first layer in a case of being seenin the direction perpendicular to the first surface, and wherein thesecond layer covers the outer edge portion.
 6. The Fabry-Perotinterference filter according to claim 4, wherein the outer surface ofthe first layer is curved so as to be away from the gap in the directionparallel to the first surface while becoming close to the substrate inthe direction perpendicular to the first surface.
 7. The Fabry-Perotinterference filter according to claim 1, further comprising: a thirdlayer that is disposed on a second surface opposite to the first surfacein the substrate.